spacer tubes and ejection charges

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Well-Known Member
Apr 7, 2004
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Hey all. I was wondering how much volume a C engine could pressurize. Is there an online source that tells the volume an ejection charge can pressurize for each motor made? Preferably the Estes (A-E) and Aerotech motors (E-G)?
There is something on info central, but you have to know how many grams of BP the charge has.
Are there any online sources that display the amounts of BP in each ejection charge for a given motor?
Originally posted by rocketsonly
Hey all. I was wondering how much volume a C engine could pressurize.

For the Estes-type motors, remember that a single 18mm BP motor will reliably eject the goods from a Big-Bertha-style rocket. That is a BT-60 (1.6 inch diam) where the pressurized volume occupies most of the 18 inch BT length. And B-class motors work just fine in that design also.

If you compare your design to the BB, you should be able to get a semi-quantitative check on how well the ejection system will work.
This also illustrates why when you launch something like a Wizard on an A8-3 that the ejection charge looks like it's going to blow the rocket to bits, and why I replace short Estes elastic shock cords with tubular Kevlar string at least 3X the length of the rocket.

Sorry to hijack, but it's a design flaw that Estes has had for 40 years that bothers me.

no kidding. I have had countless falures or separations with estes rockets. I just built a Screamin Mimi. it came with a 1/4in. elastic about 14in. long. no way I used that or there SC mount on the side of the tube. Ii used some kevalar and atached it right to the forward CR just like I do on all my HP rockets. really sweet rocket rocket though!